Process for metal casting



Patented I ch-18, 1936 I Q UNITED STATES PATENT OFFICE PROCESS FOR METALCASTING Paul C. Lemmerman, Cleveland Heights, Ohio, assigncr to TheGrasselli Chemical Company,

Cleveland, Ohio, a corporation of Delaware No Drawing. Originalapplication June 13, 1932,

Serial No.- 617,047. Divided and this application November 30, 1934,Serial No. 755,365

2 Claims. (Cl. 22-190) Refractories made of sand bonded with a solu- Theproportion of ingredients can be varied ble silicate and baked have beenused in the within certain limits. Excellent refractories have metalindustries for linings of containers for been obtained with the additionof a finely dimolten metals, for molds and in many other invided orground calcium carbonate in any of its stances where they come incontact with the forms up to 5% of the wet mixture; an amount 5 moltenmetal. of sodium or potassium silicate solids from 3 to Suchrefractories sufier from the disadvan- 7% gives about the best bond. Thecompositages that they deteriorate when stored in 9. tion of thesilicate should be of the high silica moist atmosphere a d that y asilybreak type, when using sodium silicate its composition after having beenin contact with the molten should be within the range of 2:1 to 3.6:1,SiOz m metal. to NazO. Enough water is used in the mixture I have foundthat the addition of relativ ly to produce a stiff pastewhich isself-sustaining. small amounts of calcium carbonate or other beforebaking, 1 can also add to my composialkaline earth metal carbonate tothe mixture .ti mall amounts of metal oxides, such as of sand and sodiumsilicate from which such F6 0; 0 c o which will impart to therefracrefractories are made, greatly improves the t n a-distlnctivecolor. m i h t t i en e n Strength f the The so obtained refractorieshave an initial refractory and y invention Comprises novel strengthafter baking at least equal to and in fraeteries posed of. sand, asoluble sil t most instances greater than a similar product o and thereaction product obtained from an alkamade wit t l i arbonate; afterstorage similar results.

-line 'earth metal carbonate and the mixture of f three months-1n amolst atmosphere, the sand and silicifie' the 9 of makmg such fractoriesmade according to my invention have novel refractones and from-4 to 6times the strength of a similar com- I can natural grqund limestone orwither" position made without addition of calcium carlte or precipitatedcalcium or barium. carbonate, bonate etc., in making my novelrefractories. The chemical action of the alkaline earth metal carbonateThe heat resistance for instance to tempera on the sand-silicate mixtureis not well underture of molten mm of my novel refractories is stood,though it might be assumed that some greatly F -F and t can be used slowreaction'takes place during the baking procand oval: agam fithoutbreaking ess which produces a supplementary bonding The tight bondobtained by the addition of material between the grains of the sand.When calcium carbonate does not impair the-p ro lty a more reactivecalcium compound, such as quick of the refractory and as such porosityis neceslime or hydrated lime, is incorporated into the sary to allowthe escape of gas when incontact silicate-sand mixture,arapid reactiontakes place with molten metal, these "refractories are parbut the soobtained reaction producthas practit,icula,rly pt for linings or m whichcome cally no effect upon the properties of the refrecin contact withmolten metals particularly molten tory. The so obtained insolublesilicate appears iron 7 g I to be entirely inert. While I can usevarious This application is a division of my carbonates,I prefer to usecalcium carbonate in tion Ser No 047 med June 13, 1932 its various formsas the most economical addi- I clau'm V tion to' sand-silicate mixtures.

v 1. In a process of casting metals the step of g g f g zmff myrefmtmes' I pouring the molten metal into a container lined r with aporous agglomerated, material comprisgz gs g zg ggi z ga g gt g gg flgggz ingsand, the grains of which are bonded together of 42 B. sodiumsilicate of 3.25:1, siOzi'NazO mush an anhydmus mused alkali metalratio; a self sustaining mass is formed which s ggi aggg gg zig i ggifigp of is then shaped in a mold to the desired form and n t 1 t t n dbaked at a temperature or for instance 400 F. lxflmng the 811 me a 111inner e 5 or higher, preferably in the absence of CO2 as in magglomerated mater! p contact with fire gases the silicate bond might esand the grains of which t e i t er be considerably weakened. Instead ofsodium th ou h nhydrous unfusedgldlum silicate and silicate, I can usepotassium silicate and obtain calcium silicate.

' PAUL C. LEM'MIERMAN.

